cis–trans-Amide isomerism of the 3,4-dehydroproline residue, the ‘unpuckered’ proline

• Vladimir Kubyshkin and
• Nediljko Budisa

Beilstein J. Org. Chem. 2016, 12, 589–593, doi:10.3762/bjoc.12.57

• analogues which possess a 3,4-double bond: 3,4-dehydroproline and 4-trifluoromethyl-3,4-dehydroproline. Both indicate a flat pyrroline ring in their crystal structures, in agreement with previous theoretical calculations. In solution, the peptide mimics exhibit an almost unchanged equilibrium of the trans

• axially oriented electron withdrawing substituents (4-fluoro and 4-hydroxy groups) maintained the Ks-trans/s-cis equilibrium values of the parent unsubstituted structure [39]. We also analyzed X-ray crystal structures of the Ac-Xaa-OMe models. All four compounds crystalized in the s-trans conformation: 5

• the crystal structures, this would indicate a destabilization of the transition state by the 3,4-double bond in Dhp and TfmDhp. Indeed, it is well known, that the peptidyl-Pro amide bond rotation proceeds via the syn/exo transition state, where the oxygen atom of the amide group moves under the

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• branched or unbranched starting unit. No crystal structure for PpyS exists. Therefore, the structure was modeled using OleA from Xanthomonas campestris, which is showing the highest sequence identity (27%) of all available PDB-deposited crystal structures as template. Using the generated homodimeric model

Effective in silico prediction of new oxazolidinone antibiotics: force field simulations of the antibiotic–ribosome complex supervised by experiment and electronic structure methods

• Jörg Grunenberg and
• Giuseppe Licari

Beilstein J. Org. Chem. 2016, 12, 415–428, doi:10.3762/bjoc.12.45

• growth of bacterial resistance. To date, only two crystal structures of linezolid bound to its ribosomal target are available: a) linezolid bound to the 50S subunit of Deinococcus radiodurans (DR) with a resolution of 3.5 Å [20] and linezolid bound to 50S of Haloarcula marismortui (HM) (resolution: 2.7 Å

Art, auto-mechanics, and supramolecular chemistry. A merging of hobbies and career

• Eric V. Anslyn

Beilstein J. Org. Chem. 2016, 12, 362–376, doi:10.3762/bjoc.12.40

• graphics are personal photographs by EVA, who has the copyright to every photo used herein. Representative crystal structures of various complexes we have created over the years, that in my own opinion are particularly beautiful. Collage reproduced with permission from renderings in reference [19][20][21

My maize and blue brick road to physical organic chemistry in materials

• Anne J. McNeil

Beilstein J. Org. Chem. 2016, 12, 229–238, doi:10.3762/bjoc.12.24

• gelator design. We hypothesized that the Cambridge Structural Database (CSD), which contains over 700,000 organic and inorganic crystal structures, could be used to identify molecules that exhibit 1D interactions in the solid state. The rationale was that these molecules, or closely related derivatives

• single crystals of six gelators and five nongelators. Of the six gelator crystal structures, only three had PXRD patterns that matched the gel. Within this limited data set we found 1D intermolecular interactions being present and absent amongst both gelators and nongelators, providing no clear

• distinction based on molecular packing. Next, we performed a Hirshfeld surface area analysis to quantitatively evaluate the intermolecular interactions within the crystal structures [32]. This analysis provides information about the nature and extent of intermolecular interactions in the solid state

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• from external associative complexes. UV-visible and fluorescence spectroscopy often provided useful information, while IR was rarely used. Finally, NMR and X-ray crystal structures gave more details on the inclusion mode and the interactions of the pesticide into the oligosaccharide cavity. In addition

• formation of the inclusion complex. Thus, on the basis of these last results, the formation of an internal inclusion complex was favored by the authors. In 2013, Cruickshank reported the X-ray crystal structures of the heptakis(2,3,6-trimethyl)-β-cyclodextrin (TRIMEB)–fenthion complex (complex with 2

Inclusion complexes of 2-methoxyestradiol with dimethylated and permethylated β-cyclodextrins: models for cyclodextrin–steroid interaction

• Mino R. Caira,
• Susan A. Bourne,
• Halima Samsodien and
• Vincent J. Smith

Beilstein J. Org. Chem. 2015, 11, 2616–2630, doi:10.3762/bjoc.11.281

• crystal structures containing the rocuronium ion, a well-known neuromuscular blocking agent consisting of a steroid nucleus that is highly functionalised [17], this species being encapsulated by specially designed CD derivatives [per-6-deoxy-per-6-carboxyethylsulfanyl-γ-CD and 6-perdeoxy-6-per(4

• Crystallographic Database [16], structure solution by isomorphous replacement was not possible. Both crystal structures were therefore solved ab initio by direct methods using the program SHELXD [22]. Model development involved successive difference Fourier syntheses and iterative refinement by the full-matrix

Smart molecules for imaging, sensing and health (SMITH)

• Bradley D. Smith

Beilstein J. Org. Chem. 2015, 11, 2540–2548, doi:10.3762/bjoc.11.274

• ] (Scheme 3). Many X-ray crystal structures were acquired and they provided excellent atomic scale insight. The liquid extraction and membrane transport properties were evaluated and we demonstrated symport processes that used anion concentration gradients as energy sources to drive cation transport uphill

Life lessons

• Jonathan R. Nitschke

Beilstein J. Org. Chem. 2015, 11, 2350–2354, doi:10.3762/bjoc.11.256

• emphasize the use of simple precursors to build complex products. The preparations and crystal structures of three of these products are shown in Figure 1. Each of these products was prepared simply by mixing the precursors shown in water, and each represents a different way to arrange four metal ions in

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• -1,3-tropolones and 4,5,6,7-tetrachloro-1,3-tropolones in the reaction of methylene-active five-membered heterocycles with o-chloranil using density functional theory (DFT) quantum chemical methods. Molecular and crystal structures of three representative 2-hetaryl-1,3-tropolones have been determined

Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

• Cesar Garcias-Morales,
• David Ortegón-Reyna and
• Armando Ariza-Castolo

Beilstein J. Org. Chem. 2015, 11, 1973–1984, doi:10.3762/bjoc.11.213

• is absent in compounds 3–8. The solid-state conformations of the piperidones were determined by X-ray diffraction (XRD). Crystals of 1, 3, 5, 6, and 7 suitable for XRD were obtained. The crystal structures of 3 and 5 have been previously reported [47][61][62][63]. The crystal structures of 1, 6, and

• basis (0.55 kcal/mol). In the crystal structures of 3, 5, 6, and 7, the geometric relationship between the LPE of nitrogen and the antibonding σ orbital C–H(7)eq promotes the nN→σC–H(7)eq interaction, which is caused by the N(3)–C(7)–Heq angle being near 160° (Table 1). Furthermore, the N(3) ∙∙∙C(7

Synthesis and structures of ruthenium–NHC complexes and their catalysis in hydrogen transfer reaction

• Chao Chen,
• Chunxin Lu,
• Qing Zheng,
• Shengliang Ni,
• Min Zhang and
• Wanzhi Chen

Beilstein J. Org. Chem. 2015, 11, 1786–1795, doi:10.3762/bjoc.11.194

• corresponding nickel–NHC complexes with [Ru(p-cymene)2Cl2]2 in refluxing acetonitrile solution. The crystal structures of three complexes determined by X-ray analyses show that the central Ru(II) atoms are coordinated by pyrimidine- or pyridine-functionalized N-heterocyclic carbene and acetonitrile ligands

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• bonding, metal coordination, CT interaction, π···π stacking, van der Waals interaction, etc.) play an important role in the formation of the three-dimensional (3D) crystal structures [5]. For the construction of nanostructured objects, π···π, S···S, and other weak intermolecular interactions first

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• excitation wavelength 385 nm, band gap 3.2 eV). Whilst this is less convenient than visible light, the band edge positions are consequently more powerful redox agents. Of the naturally occurring crystal structures of TiO2, anatase is superior to rutile for photocatalytic activity [12]. For semiconductor

Synthesis of racemic and chiral BEDT-TTF derivatives possessing hydroxy groups and their achiral and chiral charge transfer complexes

• Sara J. Krivickas,
• Chiho Hashimoto,
• Junya Yoshida,
• Akira Ueda,
• Kazuyuki Takahashi,
• John D. Wallis and
• Hatsumi Mori

Beilstein J. Org. Chem. 2015, 11, 1561–1569, doi:10.3762/bjoc.11.172

• 0.5 μA under a N2 atmosphere during the course of 6 days. The other chiral brown plate crystal of α’-[(R,R)-2]2ClO4(H2O) was prepared electrochemically by utilizing (R,R)-2 (5 mg) and tetrabutylammonium perchlorate (40 mg) in dichloromethane (9 mL) at 0.5 μA for 5 days. Crystal structures of achiral

• electrode: Pt, counter electrode: Pt wire, reference electrode: saturated calomel electrode (SCE)) [22]. EI-mass spectra were obtained with a JEOL JMS-AX500 spectrometer. X-ray crystallographic measurements were made on a Rigaku AFC-7R diffractometer (Mo Kα, λ = 0.71073 Å). The crystal structures were

• )- and (S,S)-2, and the preparation, and crystal structure of the radical cation salt α’-[(S,S)-2]2ClO4 [22] have been reported. In this article, we report the syntheses of novel racemic-1 and enantiopure (R,R)- and (S,S)-2 possessing one or two hydroxymethyl groups, and the preparations, crystal

Pyridine-promoted dediazoniation of aryldiazonium tetrafluoroborates: Application to the synthesis of SF₅-substituted phenylboronic esters and iodobenzenes

• George Iakobson,
• Junyi Du,
• Alexandra M. Z. Slawin and
• Petr Beier

Beilstein J. Org. Chem. 2015, 11, 1494–1502, doi:10.3762/bjoc.11.162

• (Table 2). Crystal structures of 3a (CCDC 1009848) and 3b (CCDC 1009849) were determined confirming the nature of the products. During the course of our studies, Okazaki and co-workers reported the synthesis of 3b in 84% yield under similar conditions and have shown its reactivity in various cross

A novel and widespread class of ketosynthase is responsible for the head-to-head condensation of two acyl moieties in bacterial pyrone biosynthesis

• Darko Kresovic,
• Florence Schempp,
• Zakaria Cheikh-Ali and
• Helge B. Bode

Beilstein J. Org. Chem. 2015, 11, 1412–1417, doi:10.3762/bjoc.11.152

• could be obtained due to low expression levels under all conditions tested. The homodimeric structure of OleA from Xanthomonas campestris, showing the highest sequence identity (27%) of all available crystal structures at the PDB [21], was used as a template. OleA is responsible for the head-to-head

Azobenzene-based inhibitors of human carbonic anhydrase II

• Leander Simon Runtsch,
• David Michael Barber,
• Peter Mayer,
• Michael Groll,
• Dirk Trauner and
• Johannes Broichhagen

Beilstein J. Org. Chem. 2015, 11, 1129–1135, doi:10.3762/bjoc.11.127

• synthesized a small library of nine azobenzene sulfonamides with differing substitution patterns in the 4´-position using either azo coupling reactions or the Mills reaction. We determined the π–π* band and the crystal structures of all nine compounds together with the protein crystal structure of hCAII bound

• hCAII. a) hCAII (pdb: 2vva [7]) catalyzes the hydration of carbon dioxide to bicarbonate and a proton (left) as well as the hydrolysis of pNPA to acetate and a colored phenolate (λmax = 400 nm). b) Aryl sulfonamide-containing pharmacophores of hCAII. c) Aryl sulfonamide merged to azobenzenes. Crystal

• structures for compounds 1a–i (co-solvents and/or multiple molecules in the asymmetric cell are omitted for clarity). Crystal structure of hCAII bound to 1d (pdb: 5byi). a) The terminal amine of 1d is solvent-exposed, while the azobenzene is sticking in the cavity. b) Electron-density map of 1d bound to zinc

Regioselective synthesis of chiral dimethyl-bis(ethylenedithio)tetrathiafulvalene sulfones

• Flavia Pop and
• Narcis Avarvari

Beilstein J. Org. Chem. 2015, 11, 1105–1111, doi:10.3762/bjoc.11.124

• conformation. Cyclic voltammetry measurements indicate fully reversible oxidation in radical cation and dication species. Keywords: chirality; crystal structures; molecular materials; sulfones; tetrathiafulvalenes; Introduction Chiral tetrathiafulvalene (TTF) derivatives have been addressed for the first

Indolizines and pyrrolo[1,2-c]pyrimidines decorated with a pyrimidine and a pyridine unit respectively

• Marcel Mirel Popa,
• Emilian Georgescu,
• Mino R. Caira,
• Florentina Georgescu,
• Constantin Draghici,
• Raluca Stan,
• Calin Deleanu and
• Florea Dumitrascu

Beilstein J. Org. Chem. 2015, 11, 1079–1088, doi:10.3762/bjoc.11.121

• primary cycloadduct 19 which spontaneously rearranges and dehydrogenates under the reaction conditions, to the final aromatic compounds 20. X-ray crystal structures of the starting compounds 4-(2-pyridyl)pyrimidine (6) and 4-(4-pyridyl)pyrimidine (8) Full details of the structural solution and refinements

• parent atoms were either fully occupied by carbon atoms or by nitrogen atoms, or partially occupied by carbon and nitrogen atoms simultaneously. Figure 4a and 4b show the molecular and crystal structures of 4-(2-pyridyl)pyrimidine (6). Here, all atoms in the molecule have a site-occupancy factor (s.o.f

• -pyridylpyrimidines 6–8. The 1H NMR spectra (DMSO-d6) of 4-(2-pyridyl)pyrimidine (6) and the corresponding bromides 11a–e (the aromatic region). Molecular and crystal structures of 6 (a,b) and 8 (c,d). The molecules are located on centers of inversion and their asymmetric units are labelled, disordered atoms being

Donor–acceptor type co-crystals of arylthio-substituted tetrathiafulvalenes and fullerenes

• Xiaofeng Lu,
• Jibin Sun,
• Shangxi Zhang,
• Longfei Ma,
• Lei Liu,
• Hui Qi,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 1043–1051, doi:10.3762/bjoc.11.117

• other hand, the interaction between the aryls and fullerene molecules is very important to stabilize the structure of the co-crystals as reported in the crystal structures section. For Ar-S-TTFs exhibiting E1/21 > 0.6 V, the aryl groups are more electron deficient than the phenyl [61][62]. The

• ratio of the co-crystals, this work further demonstrates that Ar-S-TTFs are promising candidates to serve as receptors for fullerenes and have diverse supramolecular structures. Crystal structures The single crystalline structure of the complex is suitable for X-ray single crystal diffraction

Tuning the size of a redox-active tetrathiafulvalene-based self-assembled ring

• Sébastien Bivaud,
• Sébastien Goeb,
• Vincent Croué,
• Magali Allain,
• Flavia Pop and
• Marc Sallé

Beilstein J. Org. Chem. 2015, 11, 966–971, doi:10.3762/bjoc.11.108

• , mastering the geometry of multicomponent redox-active systems offers a unique opportunity to fine-tuning electronic interactions within the material [43], an issue which is of prime importance for optimizing electron transport in organic materials. X-ray crystal structures of: (a) ligand L1, (b) self

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• . Oxidation: Cyclic voltammograms of compounds 1a, 2a, 3b, and 4–8 measured at a glassy carbon electrode are shown in Figure 4 [19] and redox potentials are listed in Table 1 together with the shortest TTF (C=C)–TTF (C=C) distance in each structure (obtained from the crystal structures or from DFT

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• MPTTF aromatic derivatives, whose properties and crystal structures are discussed below. Results and Discussion Synthesis Our initial synthetic efforts were focused on optimizing reaction conditions using the PrS-MPTTF derivative 7a [23] and bromoanisole 8a as starting materials (Scheme 2), as well as

• and 1.77 V, in 4e and 4f (see Figure S7, Supporting Information File 1), respectively. For the phenol derivative 4f, this oxidation is irreversible. Crystal structures Compounds 4a,b,d,e afforded high quality crystals that could be analysed using X-ray crystallography, allowing to unambiguously

• derivative has an almost planar arrangement of the TTF moiety, whereas N-alkyl derivatives show significant deviation from planarity [12]. Interestingly, the crystal structures of all four compounds feature similar packing arrangements with two crystallographically distinct molecules (Z’ = 2) with quasi

Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties

• Longfei Ma,
• Jibin Sun,
• Xiaofeng Lu,
• Shangxi Zhang,
• Hui Qi,
• Lei Liu,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 850–859, doi:10.3762/bjoc.11.95

• report [37][38], and their electrochemical activities as well as the crystal structures have been fully elucidated [38][39]. Since the redox potentials of TTFs are very important in the formation of complexes, particularly on the charge-transfer degree, the first (E1/21) and the second (E1/22) redox

• . Crystal structure The single crystals for all of the present salts were suitable for the X-ray single crystal diffraction analyses. Herein, we report the crystal structures of the typical salts (Figures 1–5), and those of the others are supplied in Supporting Information File 1. As mentioned above, the

• discuss the crystal structures of these salts, including the molecular geometry of TTFs, the structure of anions, and the packing motifs. 1·CuBr4 crystallizes in the orthorhombic Pbcn space group with half of molecule 1 and half of CuBr4 crystallographically unique (Figure 1a). The central TTF core on 1